As we’re seeing with the Browns’ Johnny Manziel, NFL teams sometimes break in rookie quarterbacks ver-ry slowly, putting in packages for them every week until they’re ready to run the whole offense. It’s been that way since Y.A. Tittle had hair.

If Manziel ever gets discouraged, he should read this quote from one of the top quarterbacks in the 1964 draft, Jack Concannon — who, like Johnny Football, was a dangerous runner. (Later that year, he threw two touchdown passes and rushed for 99 yards to help the Eagles beat the Cowboys.) Moral: Things can always be worse.

“I was at halfback for three weeks because of injuries to three of our running backs, and I didn’t care for it too much. As a matter of fact, in my first game I was at left halfback. It was against the Giants, and the Eagles had started me with three plays — a halfback pass, an end run and a fake end run with a reverse.

“That’s the way [Packers Hall of Famer] Paul Hornung started, with three plays. The only trouble was the Giants knew the three plays, and you can imagine how I felt when they started calling them [out to one another]. The first play was a reverse, and we lost about 20 yards. The next one was the end run, and I gained maybe two yards. The third was the halfback pass, and I was smeared.

“That was my introduction to pro football. I thought the league would be rough. It was even rougher than I expected.”